The pyroelectric effect has been widely used for the detection of electromagnetic radiation, see e.g. J. App. Phys. 42, 3741 (1971). Absorbed radiation causes a small temperature rise .DELTA.I of a pyroelectric crystal. The rise in temperature changes the spontaneous polarization P.sub.S of the crystal and causes a charge to flow through an external load circuit connected across the crystal. The operating temperature of the detector is sufficiently removed from the Curie point of the crystal so that the pyroelectric coefficient .lambda., as well as the dielectric constant .epsilon. and the specific heat c.sub.p of the pyroelectric crystal can be considered constant for small .DELTA.T. The electromagnetic radiation is thus determined by measuring the pyroelectric voltage transients in the external circuit.
Specifically, in infrared detection, the detector generally comprises a thin slice of triglycine sulphate (TGS) or strontium-barium niobate (SBN) cleaved or cut from a single crystal normal to the pyroelectric axis. The crystal slice is polished to a thickness generally of 10 to 40 microns, and radiation-absorbing electrodes (area 0.2-3 mm.sup.2) preferably of gold having exposed surfaces blackened are found on the major surfaces of the slice. Metal loeads are attached to electrode, e.g. by conducting epoxy, and the processed slice mounted in a hermetically sealed package having radiation transparent windows. The crystal slice is then poled with a steady field, e.g. 10.sup.4 V/cm, to form single-domain material with a polarization field across the slice.
A typical measuring circuit is shown in FIG. 1 of the drawing hereto. A variable load resistor (10.sup.6 - 10.sup.12 ohms) is connected in parallel with the pyroelectric crystal, and a field-effect transistor source-follower circuit is connected as shown in FIG. 1. The pyroelectric voltage transients are measured on an oscilloscope (CRO) with a standard (e.g. 3A9) amplifier. Such detectors have been able to provide as low as 0.01 to 0.1.degree. K sensitivity.
The main difficulty with such pyroelectric radiation detectors has been the bulk and expense of the detector as well as the accompanying measuring circuit. Also, the detector has been generally subject to high noise levels. The present invention overcomes these difficulties, and provides a pyroelectric electromagnetic radiation detector which can be fabricated and operated compatibly with large scale integrated circuits. Further, the pyroelectric detector of the present invention is considerably less noisy than previous pyroelectric radiation detectors.